Apologies for the inconvenience caused to you due to this issue.
Unfortunately we are not able to reproduce this issue. Could you kindly provide the following information to help us nail this down.
1)Kindly try the below workaround and let us know if that helps with the issue:
Kindly rename your Preferences folder placed in below location and share this folder with us in a zip file.
MAC: /Users//Library/Preferences/Adobe Illustrator 24 Settings//
WIN: C:\Users\\AppData\Roaming\Adobe\Adobe Illustrator 24 Settings\
Kindly share the above with us in a Zip file at ShareWithAI@adobe.com
Please mention the title of this issue as the subject of the mail.
An error occurred while saving the commentPierce McConnell commented
I just experienced this same problem in April 2020. The thing that worked for me was suggested by Hans. Close Illustrator > Open Illustrator, but not a file > While on the home menu, select window>workspace>choose a default workspace (I chose typography). That seemed to unstick something. Then, I could switch back to my custom workspace and the menu functioned normally again.